Fuel pump for internal-combustion engines



Jimo 13, 1931.

L. H. WHEELER FUEL PUMP FOR INTERNAL` COMBUSTION ENGINES Filed Nov. 16

Patented Jan. 13, 1931 UNITED STATES PATENTFOFFICE l LEONARD H.- WHEELER, OF CHICAGO, ILLINOIS, .ASSIGNOR TO STEWART-WARNER CORPORATION, F CHICAGO, ILLINOIS, A CORPORATION OF'VIRGIN'IA FUEL PUMP FOR INTERNAL-COMBUSTION ENGDSI'ES Application filed November 16, 1928. Serial No. 319,959.

The purpose of this invention is to provide an improved construction of a pumping device foi-'supplying fuel to an internal combastion engine in which the pumping element derives actuation from a positively actuated part through the medium of an elastically compressible fluid as atmospheric air,

as distinguished from being positively actuated in either direction by the positively actuated part. The inventicn consists in the elements and features of construction shown and described as indicated in the claims.

In the drawings Figure l is a top plan view ciE pumping structure embodying this invention.

Figure 2 is a section at the line 2-2 on Figure 1 showing the parts in normal posi- `tion of rest or as at' the limit of the feeding stroke of the pumping` element.

Figure 3 is a. view similar to Figure 2 showing the part-s in position which they may occupy at the opposite limit of the movement of the actuating lever.

Referring to the 'drawings for observing the structure in general, it may be understood to comprise a diaphragm pumping device having intake andI discharge. and check valves controlling inow and outflow openingfor one-way flow through the pumping chamber and seating -against reverse flow. The diaphragm of this pump may be seen to be stressed byga spring, 27, in the direction of its feeding strokefand the chamber at the sidcof the diaphragm in which this spring is situated. being at the .opposite side from the pumping chamber, will be seen to be connected with the cylinder of a piston pump of which the piston is actuated by connection with a lever which in turn is .actuated by a -caln on a shaft of the engine; and the means by which the piston, positively actuated by the engine cam, communicates movement to the diaphragm, consists merely of the air enclosed between the turn stroke of the piston being produced by a spring reacting on the piston stem and servmg at the same time to hold the lever in touch with the cam. A special characteristic of the' construction may be noticed, namely that the piston cylinder is provided with air vent ap` ertures which are passed by the piston in its suction stroke, admitting air to the pis-l ton chamber for restoring the pressure therein to atmospheric, before the returnstroke of the piston which is causedby thespring mentioned. In said return` stroke the air passes by the cup leather so readily that very little pressure for discharge is due to the piston return stroke. the discharge pressure being almost wholly afforded by the reaction of the spring, 27.

Referring to the drawings for details of construction z--The pump body comprises parts A'and B between which the diaphragm C is clamped, the part A having the recess, 20, spanned by the diaphragm and constituting the pumping chamber. and having the intake' passage.` 21, controlled by the inlet .check valve. 22, and discharge passage, 23,

ber. 40. in which the piston,32. is reciprocated as hereinafter described. The `pump body comprises a third part, D, by which the pump body in its entirety is adapted to be mounted upon the body of the engine from which actuation of the pumping structure is to be derived, said pump body part. D, being chambered and having its chamber. 41, communitinuation of the piston chamber and open at the end at which the structure is arranged for mounting on the engine, so' that the cavity of the pump body part. D. communicates with the crank case of the engine. The piston, 32,

is arranged to be actuated in one-direction by a cam, F, on a cam shaft, E. through the medium of the lever. 10, fulcrumed at 11 on the end portion of the pump body member,

cat-ing with and constituting substantial conv D, whichv protrudes into the crank case, and has its inner end in the cra-nk case overhanging the cam, F, foractuation by the latter as mentioned, the opposite end of the lever being pivotally connected at 12 with the stem, 37, of the piston, 32. The pump body member, D, is provided at its lower side with a pocket for seating and positioning a coil spring, 42, -having at its upper end a cap disk, 43, which reacts upon the piston,j32,` through the medium of its stein and the lever 10, the latter having at the end at which it is pivoted to the piston stem a downwardly projecting lug, 15, for seating in the cap, 43, at the head of the spring to insure the maintenance of proper connection between the parts for causing the spring to react as stated.

The piston, 32, comprises disks, 33 `and 34, between which there is clamped a single cup leather, 35', which has its flanged margin for giving it the cup from extending downwardly, and the lower disk, 33, is slightly lessin diameter than the upper disk, 34,`to permit the cup leather to yield downwardly in the up-stroke of the piston, so that it operates as a check valve seating for perfect piston action in the down-stroke of the piston and yielding to permit the fluid above to passm it in the up-stroke of the piston. At a point in the length of the piston chamber toward the lower limit of the'stroke of the piston there are formed atmosphere vents, 45, which are passed by the piston in its down-stroke in which it operates positively for suction, that is, producing a rarefied condition of the air above it in the piston chamber and in the air chamber, 30, below the diaphragm, so that when in this down-stroke the piston passes the atmosphere vent ports, the vacuum produced above the piston in that' stroke is relieved by the entranceC of air through said ports and the diaphragm, C, which has been flexed downwardly in said suction stroke of the piston, is relieved from the suction and left free to be returned for its feeding stroke by the reaction of a spring, 27, seated at its lower end on the partition, 28, between the air chamber, 30, and the piston chamber, 40, around the port, 31. And it will be observed that in the return stroke of the piston caused by the spring, 42, the air between the diaphragm and the piston is forced past the piston and the pressure in the piston chamber below the piston and in the cavity of the pump body part, D-` will be substantially atmospheric, and that this return strokek of the piston will not operate to any material extent for giving the diaphragm its feeding stroke so that that stroke will be-given by the stress, only of the spring, 27. And it will be under- `stood that the 'air taken in through the atmosphere vent ports, 45, will mainly be driven into thecrank case, but that opportun- `ity is afforded for relieving anypressure thus produced in the crank case by the uparound the stroke of the piston passing the atmosphere i -vent ports, 45, so that the connection ofthe device with the engine crank casehas no tendency to interfere with the operation of the engine.

The drawings show the pump body part, A, having formed integrally with it a part, A1, which extends o" horizontally. at and above the parting pla-ne between the pump parts, A and B, sald extension, A1,. having the fuel intake connection and intake valve, and having mounted on it the parts constituting a familiar form of strainer or filter for the fuel through which is passes before entering the pumping chamber. This construction is familiar, but for the identification of the several parts may be further described in detail as follows: A bored and tapped passage, 70, affords connection for afuel pipe leading from the fuel source. A port, '71, opening from the passage, 70, admits the fuel to the fuel cup, 72, which is clamped to the part, A1, by the yoke, 73, operated for tightt enlng by a cam lever, 74. A boss, 75, projecting downwardly from the part, A1, serves for mounting the strainer or filter member, 76, which depends in the-cup, 72, and the part, A1, is bored from the upper end in line with said boss, the bore being counterbored at the upper end toY within a short distance of the lower end of the boss to afford a valve seat, and a pipe member, 77, is joined tothe boss at theklower end protruding up slightly into the counterbore to form by its upper end the seat for the inlet check valve, 22, above, mentioned, a plug, 78, being screwed into the upper end of the counter- 'bore having a central pin, 79, projecting downward for stopping the openlng movement of thecheck valve at a proper distance from its seat. A` spring, 80, is,interposed in between the check valve and the head of) the plug for reacting on the spring to insure its normal seating The intake passage, 21,' above mentioned extends in part, A1, to the counterbore through which the fuel passing the vcheck valve, 22, reaches said intake passage, 21.

Upon considering the operation of this construction it will be seen that the feeding stroke of the diaphragm pump, being effected by the reaction of the spring` 27, may

'be liniited by the adjustment of the spring as cession of the piston strokes which are positively caused by the cam on the engine shaft in not exceeding one-half of the revolution of said shaft will not ordinarily be respondbetween the positively actuating means and the pumping member, whether it be a diaphragm or piston, as found in certain other types, is liable to be rapidly destructive of the operative parts, and, in any event, is effective for lifting the fuel only for a very small portion of each positive stroke. By

the interposition of the elastic means of communicating the suction stroke consisting in the air which is exhausted by the suction stroke,-which is the positive stroke,-of the piston, the force exerted by the action of the cam on the lever and thereby on the piston may be said to be trapped in the air space between the piston and the diaphragmin which the condition of partial vacuum is produced by the suction stroke of the piston, and this trapped force, reacting during the return stroke ofthe piston, has time to overcome the inertia of the fuel and to cause it to move throughv the passages leading to the pumping chamber. Thus there is obtained for movement of the fuel the entire time of the suction stroke.

I claim:

l. In a pump for supplying fuel to an internal combustion engine, in combination witha casing having two cavities in communication with each other; a flexible diaphragm partitioning one of said cavities to form atone side of the diaphragm a pumping chamber, and at the opposite side an air chamber; a spring reacting on said opposite side of the diaphragm to hold the latter normally flexed in the direction for reducing the pumping chamber and enlarging the air chamber, the pumping chamber having inflowand outflow passages and valves controlling them respectively, for one-way flow through the pumping chamber; the second cavity comprising a piston chamber, the communication mentioned being between the air chamber and said piston chamber; a piston reciprocably mounted in the piston chamber; a spring reacting on the piston in the direction for holding it normally inthrust in the pistonl chamber to-wa-rd the air chamber; means for positively retracting the piston in opposition to said spring away from the air chamber for exhausting the latter of air through the communication between the two chambers, and retracting the diaphragm in pumping chamber enlarging direction, the piston chamber having an atmospheric vent port past which the piston is retracted in said positive stroke; whereby the piston chamber and the air chamber are vented and the diaphragm is thrust by its spring in pumping chamber reducing and fuely feeding direction.

2. In the construction defined in claim l,

the piston being constructed for limited passage of air past it in'its spring-caused thrust toward the air chamberand for positve forcing of the air in its opposite stroke, the cas- 4ing being arranged to be mounted on the en- .fgine crank case, and with the cavity which comprises the piston chamber communicat- -ing with the interior of the crank case, whereby air entering the piston chamber through the vent ports is forced into the crank case.

3. In a construction for the purpose indicated, a diaphragm pump comprising casing members, and a diaphragm clamped between them, the casing member at one side of the diaphragm having a recess spanned by the diaphragm forming the pumping chamber, said chamber having fuel inflow and outflow connections valve-controlled for oneway How of the fluid pumped through the pumping chamber, the casing member at the opposite side having a recess spanned by the diaphragm constituting an air chamber, and a pump connected for exhausting the air from the air chamber for giving the diaphragm its suction stroke, and a spring reacting on the pump diaphragm in the same direction kas the air pressure from the air pump, the air pump being arranged to wit-hdraw air from the air chamber into the air pump in the early part of the suction stroke of the air pump for producing vacuum in the air chamber of the diaphragm pump in that part of its stroke, the air pump having an atmospheric vent which is uncovered in the latter part of the piston stroke to relieve the vacuum in the air pump chamber and in the air chamber of the diaphragm pump, permittingthe diaphragm spring to react on the diaphragm for giving it its pumping stroke free from restraint due to vacuum developed in the early part of the stroke.

. 4.v A construction for the purpose indicated comprising casing members and a diaphragm clamped between them,4 the casing member at one side ofthe diaphragm having a recess spanned by the diaphragm forming the pumping chamber, said chamber having fuel inflow and outflow connections valvecontrolled for one-way flow of the fluid pumped through the pumping chamber, the casingmember at the opposite side having a recess spanned by the diaphragm constituting an air chamber, the second mentioned casing member having a piston chamber in free communication with the air chamber of the diaphragm pump, and a piston reciprocablyl mounted in said piston chamber for movement toward and from the end of the piston .chamber at which it communicates with the air chamber, said piston being constructed and arranged for piston fit in the lchamber in its stroke away fromthe air chamber port, and for relatively free move- -ment of air past it in the opposite stroke;

whereby its reciprocation operates for suction .on the diaphragm; means mounted in the casing connected with the piston for positive actuation of the piston in the direction of said piston it, and a spring reacting on the piston for its return stroke.

5. In a fuel pumping apparatus for supplying an internal combustion engine, a. diaphragm pump comprising a pumping chamber and an air chamber, a flexible diaphragm separating the two chambers, said pump being connected 'for deriving fuel by suction from the lower source and delivering it by pressure to the engine; means for giving the diaphragm its suction movement consisting of a piston suction pump having 'its intake connected with the air chamber of the diaphragm pump, and means for reciprocating the piston, the piston operating means of the piston 'pump being arranged for positive actuation of the piston in its intake stroke, and the piston chamber being co-operatively constructed for passing the air by the piston in the return movement of the latter from the intake stroke.

6. In a fuel pumping apparatus for supplying an internal combustion engine, a diaphragm pump comprising a pumping chamber and an air chamber, a iexible diaphragm separating the two chambers, said pump being connected for deriving fuel by suction from a lower source and delivering it by pressure to the engine; meanslfor giving the diaphragm its suction movement consisting of apiston suction pump having its intake connected with the air chamber of the diaphragm pump, and means for reciprocating the piston, the piston being provided with 'only one cup leather for its piston lit in the cylinder, said cup leather having its marginal ange turned in the direction of the intake stroke of the piston, whereby the suction action of that stroke is positive, and the air by-passes the piston in the'opposite stroke.

7. In a fuel pumping apparatus for supplying an internal combustion engine, a diaphragm pump comprising a pumping chamer and an air chamber, a flexible diaphragm separating the two chambers, said pump being connected for derivin fuel by suction from a lower source and delivering it by pressure to the engine; means for giving the diaphragm its suction movement Vconsisting of a piston-suction pump having its intake connected with the air chamber of the diaphragm pump, and means for reci rocating the piston, the piston chamber o the piston pump having an atmospheric vent at a point in the pistons path which is passed by the piston in the latter part of the intake stroke, whereby the vacuum developed in said intake stroke is released at the finish of the stroke.

separating the two chambers, said pump being connected for derivin fuel by suction from a lower source and delivering it by pressure to the engine; means for giving the diaphragm its suction movement consisting of a piston suction pump having its intake connected with the air chamber of the diaphragm pump, and means for reciprocating the piston, the piston operating means of the piston pump being arranged for positive actuation of its piston in the intake stroke, and said piston and piston chamber being co-operatively constructed for passing the air by the piston in the return movement of the latter from it-s intake stroke, and resilient means for giving the piston its return stroke.

9. Ina fuel pumping apparatus for supplying an internal combustion engine, a diaphragm pump comprising a pumping chamber and an air chamber, a exible diaphragm separating the two chambers, said pump being connected for deriving fuel by suction from a lower source and delivering it by pressure to the engine; means for giving the diaphragm its suction movement consisting of a piston suction pump having its intake connected with the air chamber of the diaphragm pump, and means for reciprocating the piston, the piston being provided with only one cup leather for its piston t in the cylinder,

said cup leather having its marginal ange turned in the direction of the intake stroke, whereby the* suction action of that stroke is positive, and the air by-passes the piston in the opposite stroke, and resilient means for giving the piston its said opposite air return stroke.

l0. In a fuel pumping apparatus for supplying an internal combustion engine, a diaphragm pump comprisingJ pumping chamber and an air chamber, a flexible diaphragm separating the two chambers, said pump being connected for deriving fuel by suction from a lower source and delivering it by pressure to the engine; means for giving the'diaphragm its suction movement consisting of a piston suction pump having its intake connected with the air chamber of the diaphragm pump, and means for reciprocating the piston, the piston chamber of the piston pump having an atomspheric vent at a point in the pistons path which is passed by the piston in the latter part of its intake stroke, whereby the vacuum developed -in said intake stroke is released at the finish of said stroke, the piston operating means of the piston pump being arranged for positive actuation of the piston in its intake stroke, and said piston and the piston chamber beingco-operative- 1y constructed for passing the air by the pistonin the return movement of the latter in its intake stroke.

11. In a fuel pumping apparatus for supplying an internal combustion engine, a diaphragm pump comprising a pumping cham- Elli I phragm partitioning air chamber,

' tioned Ifor holding the vsisting of a piston suction pump having its chamber of the and means for reciprocat- A exhausting the air chamber and ber and an air chamber a flexible diaphragm separating the two chambers, said pump being connected for deriving fuel by suction from a lower source and" delivering it by pressure to the engine;means. for givlng diaphragm its suction movement conintake connected with the air diaphragm pump, ing the piston, the piston chamber of the piston pump having an atmospheric vent at a point in the pistons path which is passed by the piston in the latter part of its intake stroke, wherebythe vacuum developed in said intake stroke isreleased at the finish of said stroke, the pistonoperating means o the piston pump being arranged for positive actuation of the piston in its intake stroke, and said piston and the piston chamber being co-operatively constructed for passing the air by the piston-in the return movement of the latter 1n its intake stroke,`and resilient means for giving the piston its return stroke.

12. In a pump for supplying fuel to an internal combustion engine, in combination with a casing`having two ,cavities in communication with each other, a flexible diathe first of said cavities to form at one side ofthe diaphragm a pumping chamber and at the other side an the second cavity, comprising a piston chamber,

tioned being between the air chamber and said piston chamber; a spring reacting on they diaphragm conditioned for holding it normally flexed in the fuel discharge rection; a second spring reacting on the piston condithe piston normally inthrust in the piston chamber; meansfor positively retracting the piston in opposition to said second spring for thereby giving the diaphragm its fuel intake movement a ainst thereaction of the rst spring, the piston being formed for air movement past v1t in its opposite stroke; whereby the successive strokes `of the piston operate for building up the reaction of the irstspring on the dia- A phragm for the fuel feeding action of the latter.,

I n testimony whereof, I have hereunto set my hand at Chicago, Illinois, November, 1928. a v LEONARD'H. WHEELER.

the communication menchamber toward the'air l this 9th day of 

